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Construction of Z-Scheme g-C3N4/RGO/WO3 with in situ photoreduced graphene oxide as electron mediator for efficient photocatalytic degradation of ciprofloxacin

Lu, Na, Wang, Pu, Su, Yan, Yu, Hongtao, Liu, Ning, Quan, Xie
Chemosphere 2019 v.215 pp. 444-453
carbon nitride, ciprofloxacin, dielectric spectroscopy, electric current, electron paramagnetic resonance spectroscopy, electron transfer, graphene oxide, hydroxyl radicals, photocatalysis, photocatalysts, photoluminescence, superoxide anion, trapping, tungsten oxide
Z-scheme photocatalyst g-C3N4/RGO/WO3 with reduced graphene oxide (RGO) as the electron mediator was synthesized via a facile photoreduction method. According the results of photoluminescence (PL), electrochemical impedance spectroscopy (EIS) and photocurrent response, g-C3N4/RGO/WO3 presents more efficient separation of charges and enhanced electronic mobility than g-C3N4/WO3, g-C3N4 and WO3, which benefits from the excellent electron transfer property of RGO. Reactive species trapping experiments and electron paramagnetic resonance (EPR) test demonstrated that superoxide radical (O2−) and hydroxyl radical (OH) were produced because of the high redox capacities caused by the unique transfer behaviors of charges in Z-scheme photocatalyst g-C3N4/RGO/WO3. In the absence of RGO as electron mediator, only holes (h+) participates the degradation process of ciprofloxacin (CIP) due to the decreased redox capacities of g-C3N4/WO3 compared with g-C3N4/RGO/WO3. Therefore, the degradation rate of Ciprofloxacin (CIP) over g-C3N4/RGO/WO3 composite was nearly twice as much as that over g-C3N4/WO3. In addition, the analysis of intermediates provides insight into the degradation pathway of CIP.